KCNQ1 Variant D488G Detail

We estimate the penetrance of LQTS for KCNQ1 D488G is 11%. We are unaware of any observations of this variant in individuals. D488G is not present in gnomAD. D488G has not been functionally characterized. This residue is located in a Non_Hotspot region for LQT1. In silico predictions, functional data (if available), and location in structure are equivalent to observing 1 individuals with LQT1 and 9 unaffected individuals. These data combined with observations of carriers lead us to estimate the LQTS penetrance for KCNQ1 D488G around 11% (1/10).

In Silico Data

PROVEAN PolyPhen-2 BLAST-PSSM REVEL Penetrance Density (%)
-2.94 0.037 -1 0.776 1
PROVEAN scores less than -2 are considered deleterious. REVEL scores higher than 0.5 or 0.75 are considered likely pathogenic (higher sensitivity with the former cutoff, higher specificity with the latter cutoff). A PolyPhen-2 score of 0.85 or greater is considered likely pathogenic. BLAST-PSSM reflects the evolutionary conservation of residue substitutions, more negative numbers indicate fewer observations of the specific substitution than is expected. Penetrance density is our previously published method to calculate the average LQTS probability density in a shell of residues surrounding a residue of interest (Kroncke et al. 2019).

Reported Carrier Data

PubMed ID Year Carriers Unaffected LQT1 Other Disease
Summary totals might not agree with the literature table because of duplicate patients, which were excluded from the total counts. We do not distinguish here between multiple missense codons. Missense variants are combined across degenerate codon substitutions since codon-level data were not consistently available for curation.

D488G has 31 previously observed neighbors within 15 angstroms

A residue within a folded protein on average has nearest neighbors that fall roughly into two shells: a "nearest" neighbor around 5-6 angstroms and a second shell around 11 angstroms. NOTE: some residues appear multiple times at different distances. This results from the fact that the functional KV7.1 channel is a homotetramer and occasionally the same residue from multiple subunits is present within the 15A window. All variants shown in the rightmost column have been observed in at least one individual in the literature or gnomAD.

Neighbor Distance (Angstroms) Variants Observed in Individuals
488 0 D488E, D488E,
487 4 E487K,
489 4
486 5 A486T,
490 5
485 7 F485S,
491 7
484 8
492 8 L492ins,
483 8
493 8 G493A,
482 9 T482N, T482A, T482S, T482S,
494 9
481 10
495 10 T495S, T495S, T495A,
480 11 M480T,
496 11
479 11 F479L, F479L, F479L,
497 11 L497P,
478 12 H478Y,
498 12
477 13 P477L, P477T,
499 13 P499S,
476 13 M476L, M476L, M476V,
500 13 I500L, I500V,
475 14
501 14 T501A,
474 14
502 14
473 15 E473Q,
503 15